A novel ultrafine polyethylene/silica composite particle with core-shell structure was prepared by the sol-gel method in the presence of the melt polyethylene emulsion. A series of samples with different polyethylene content were prepared to investigate the unique characteristics of this original composite particle. The core-shell structure and composition of the composite particle was proved by the transmission electron microscopy observation and Fourier transform infrared spectra. The composite particles possess a spherical morphology and the mean size is about 160nm, presented by the scanning electronic microscope observation and nanoparticle tracking analysis, respectively.